Lock a 10-year fix at today's quoted rates and you trade short-term flexibility for long-term certainty. That trade-off has a cost most coverage misses: if mortgage rates fall meaningfully during the fix, an Early Repayment Charge (ERC) acts as a hard floor on the rate-drop the borrower can profitably react to.
This piece works through the maths on a £270,000 mortgage at 4.85% over 30 years — a standard sticker-rate snapshot for a 10-year fix in spring 2026 — and shows exactly how big a rate fall has to be, year by year, before paying the ERC and remortgaging actually saves money.
What an ERC is, and why long fixes have them
An Early Repayment Charge is a contractual fee the lender deducts if the borrower repays a fixed-rate loan ahead of the end of its fixed period. On UK regulated residential mortgages, the size and tapering schedule of any ERC must be disclosed up-front in the European Standardised Information Sheet (ESIS) under the FCA's MCOB rules — specifically MCOB 12.3, which requires the charge to be "a reasonable pre-estimate of the costs as a result of the customer repaying the amount due under the regulated mortgage contract before the contract has terminated".
Two-year and five-year fixes carry shorter ERC windows. Ten-year fixes carry longer, deeper schedules. The most common pattern across the high-street book — Halifax, Nationwide, HSBC and similar — is a tapered 1-5% slide across the first five years:
| Year of fix | Typical ERC (% of outstanding balance) |
|---|---|
| Year 1 | 5% |
| Year 2 | 4% |
| Year 3 | 3% |
| Year 4 | 2% |
| Year 5 | 1% |
Some 10-year products run that taper across all ten years; others (such as flexible 10-year products like Habito One, April Mortgages, Perenna) front-load ERCs into a five-year window and then go ERC-free. Read the ESIS — the schedule is in the product-specific Section 9.
The hard-floor question, framed cleanly
The borrower's question is simple: if rates fall meaningfully during my fix, can I pay the ERC, remortgage to a new product at the lower rate, and come out ahead?
Answer: only if the rate drop on the new product is large enough that the interest saved over the remainder of the original fix horizon exceeds the ERC plus any new arrangement fee.
That is the hard-floor logic. The ERC isn't a punishment — it's an option-value cost the borrower has implicitly bought when they took the long fix. They paid for certainty against rates rising; the price of that certainty is the foregone ability to capture rates falling.
Year-by-year breakeven on the £270k baseline
The same £300,000 purchase / £270,000 / 30-year / 4.85% baseline used through the fix-length sensitivity analysis on a £300k buy-vs-rent decision, now with the ERC layered on. Monthly payment is £1,424.77.
Amortisation gives the outstanding balance at each year-end. Multiplying by the ERC percentage gives the £ amount that has to be recouped by the rate drop over the rest of the original 10-year horizon. The breakeven rate-drop is then solved numerically so that the interest saved over the remainder equals the ERC (and, optionally, a £999 product fee on the new deal):
| End of year | Outstanding balance | ERC % | ERC £ | Months left in fix | Breakeven rate drop (no fee) | Breakeven rate drop (+£999 fee) |
|---|---|---|---|---|---|---|
| Year 1 | £265,908 | 5% | £13,295 | 108 | 57 bps | 62 bps |
| Year 2 | £261,612 | 4% | £10,464 | 96 | 51 bps | 56 bps |
| Year 3 | £257,104 | 3% | £7,713 | 84 | 44 bps | 50 bps |
| Year 4 | £252,372 | 2% | £5,047 | 72 | 34 bps | 41 bps |
| Year 5 | £247,405 | 1% | £2,474 | 60 | 20 bps | 29 bps |
Calculated against the cycle-baseline amortisation schedule; remaining-term assumed unchanged on the new product. Data: amortisation maths, ERC tapers from standard high-street published ESIS files (2026 sample).
Read the table this way: at the end of year three, with the loan balance down to £257,104, the 3% ERC is £7,713. To make remortgaging worthwhile, market rates on a comparable 75% LTV product have to be at least 44 basis points below 4.85% — i.e. below 4.41%. If the new product carries a £999 arrangement fee, the threshold tightens to 50 bps, so below 4.35%.
The shape of the curve is the interesting bit. The breakeven drop is largest in years 1-2 (57-62 bps), because the ERC is high but there's still seven-plus years left for a lower rate to amortise the cost. It is smallest in years 4-5 (20-29 bps), because the ERC has tapered toward 1% but the runway has shortened to five years. Year 3 sits in the middle.
What this maps onto in spring-2026 reality
The Bank of England's effective interest rates statistical release shows the 75% LTV 5-year fixed advertised rate at 4.32% as of April 2026 — already 53 bps below the 4.85% used as the 10-year sticker rate in this worked example. That puts a year-3 remortgage just over the no-fee breakeven (44 bps) but just under the with-fee breakeven (50 bps), depending on whether the borrower can secure a fee-free product.
Applied to the year-3 borrower on the worked example, the net cash position over the remaining 84 months looks like this:
| New product rate | New monthly payment | ERC paid | Net saving over 84 months (incl. balance differential) |
|---|---|---|---|
| 4.32% (April 2026 BoE 75LTV5Y print) | £1,345.58 | £7,713 | +£1,569 |
| 4.20% | £1,327.98 | £7,713 | +£3,660 |
| 4.10% | £1,313.40 | £7,713 | +£5,399 |
| 4.00% | £1,298.91 | £7,713 | +£7,134 |
| 3.85% | £1,277.33 | £7,713 | +£9,733 |
| 3.50% | £1,227.74 | £7,713 | +£15,767 |
Two things to flag. First, the "raw" monthly cash saving at the BoE April 2026 print rate is actually slightly negative over 84 months (the ERC alone outweighs the lower payments). The net saving turns positive only when the balance differential is accounted for — the lower rate means each new monthly payment kills more principal, leaving the borrower with a smaller outstanding balance at the end of the fix horizon. That is real value but it is not cash in pocket; it is equity on paper.
Second, none of these scenarios are advice. The rate the borrower can actually secure depends on their LTV at remortgage (a falling-price environment moves them up the LTV ladder), their lender's appetite, the product fees in their personal ESIS, and their own affordability assessment at the time of switch.
What ERCs do to the "free option"
There's an option-pricing way to read all this. A short fix gives the borrower the right — but not the obligation — to reset to whatever the market rate is, every two or five years. A long fix sells that right to the lender in exchange for certainty.
The ERC is the price of buying part of that right back. In years 1-2 it costs roughly 60 bps of rate drop to buy the option back. In year 5 it costs 20-30 bps. After the ERC window ends (typically year 6 on the longer-tapered products), the option is "free" again — the borrower can remortgage without penalty, capturing whatever the market has done.
This is why the 10-year fix's certainty premium — quantified at about £85/month over a flat-scenario 5-year fix in the cycle-baseline analysis — isn't purely a "rate rise" hedge. It's also a foregone "rate fall" upside, capped by the ERC schedule.
The same logic applies in reverse to two-year fixes: the borrower keeps the option to capture rate falls cheaply, but pays for it by re-pricing into whatever rates exist in 24 months. The rate stress test on the buy-vs-rent breakeven walked through the rising-rate side of that trade; this piece is its falling-rate mirror.
Three practical caveats
1. ERC schedules vary by lender and product. The 1-5% sliding taper above is the most common pattern but is not universal. Some products have a flat 5% throughout the fix; others (notably the flexible long-fix products) cluster ERCs into the first five years and drop to zero thereafter. Always read Section 9 of the personal ESIS — it is the only source that binds the borrower's actual lender.
2. Product fees compound the threshold. The breakeven figures above use a £999 product fee as the illustrative load. Real product fees in the 2026 mortgage market sit anywhere from £0 (cashback products) to £1,995+ (sub-rate buydown products). Higher fees push the breakeven rate-drop further from current sticker rates. The arrangement-fee mechanics on monthly cost piece in this cluster works through how the same fee changes the headline monthly figure across fix lengths.
3. The maths above assumes no overpayment. Most 10-year fixes allow 10% annual overpayments within the fix without triggering an ERC. A borrower who is regularly overpaying erodes the outstanding balance faster than the standard amortisation curve, which lowers each year's ERC £ figure and tightens the breakeven rate-drop. The overpayment-impact analysis on the equity curve sibling piece quantifies how that compounds.
Try it on a real number
Homecost's True Cost calculator surfaces the monthly payment, lifetime interest and amortisation curve for any combination of price, deposit, rate and term, and lets the comparison engine line up two products side-by-side with their fee structures. To see how a remortgage in year 3 would actually compare against staying in a 10-year fix on a property you're looking at, pick a representative postcode (e.g. M1 1AE) and run the numbers in the mortgage comparison calculator.
For other angles of the buy-vs-rent and fix-length cluster, see the full Cost Intelligence section.
Disclaimer
This article is general information about how Early Repayment Charges work on UK residential mortgages, not advice. The breakeven figures use a representative loan size, term and rate; your personal ESIS, your lender's specific ERC schedule, your LTV at remortgage, your affordability position and any product fees will all change the answer. Speak to a qualified mortgage broker or independent financial adviser before paying an ERC or arranging a remortgage.
Sources: amortisation calculations on a £270,000 / 30-year / 4.85% baseline; ERC tapers from standard 2026 high-street ESIS schedules; Bank of England effective interest rates release (April 2026 print, 75% LTV 5-year fixed advertised); FCA MCOB 12.3 rule text. Based on 39 monthly observations in the Bank of England published mortgage-rate series and the cycle-baseline amortisation maths — see the Homecost blog for the wider methodology cluster.